There were impassioned speeches with equal rights, voting rights and immigration rights all placed firmly in front of the cameras.

The tone was set early with host Neil Patrick Harris' satirical welcome for "Hollywood's best and whitest - sorry brightest" - a dig at the absence of black actors from the main awards.

But it was Patricia Arquette who got things rolling - bringing the house down with a speech demanding "equal rights for women".

Accepting her best supporting actress Oscar, she said: "To every woman who gave birth, to every taxpayer and citizen of this nation, we have fought for everybody else's equal rights. It's our time to have wage equality once and for all and equal rights for women in the United States of America."

The night's most rousing speech was delivered by John Legend when the singer accepted the Oscar for best original song for Glory from the Martin Luther King biopic Selma.

Collecting the award, Legend said: " We know that the Voting Rights Act that they fought for 50 years ago is being compromised right now in this country today."

He said the song was written for a film based on events 50 years ago, but he added: "We say that Selma is now because the struggle for justice is right now."

He added: "We know that right now the struggle for freedom and justice is real. We live in the most incarcerated country in the world.

"There are more black men under correctional control today than there were under slavery in 1850."

A quieter - but no less powerful - speech was delivered by Graham Moore who won the Oscar for best adapted screenplay for The Imitation Game which stars Benedict Cumberbatch as Alan Turing.

The writer told the audience he tried to commit suicide aged 16 because he "felt weird" and "different" and told the TV audience: "Stay weird, stay different and when it's your turn and you're standing on this stage, please pass on this message".

Best director winner Alejandro G Inarritu raised the plight of Mexicans inside and outside the US, saying: "I pray for my fellow Mexicans, to have the government they deserve"

The award for best documentary feature went to Citizenfour, about whistleblower Edward Snowden, and director Laura Poitras dedicated the win to him and other whistleblowers, and journalists "exposing truth".

In a nod to the controversy over the release of The Interview, Academy president Cheryl Boone Isaacs told the assembled audience they had "a responsibility to protect freedom of expression".

The film, about a plot to assassinate North Korean leader Kim Jong Un, had its US release cancelled late last year following a hacking plot of the Sony Pictures studio in which terror threats were made against cinemas planning to screen it.

It was at the centre of an international controversy after the FBI insisted the online attack was carried out by North Korea and, after much political and celebrity pressure, the film was eventually shown online and in a limited number of cinemas.